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[209.132.180.67]) by mx.google.com with ESMTP id z3si19093487ejx.33.2019.09.16.06.57.26; Mon, 16 Sep 2019 06:58:00 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388140AbfIPNzH (ORCPT + 99 others); Mon, 16 Sep 2019 09:55:07 -0400 Received: from mx1.emlix.com ([188.40.240.192]:49150 "EHLO mx1.emlix.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728005AbfIPNzH (ORCPT ); Mon, 16 Sep 2019 09:55:07 -0400 Received: from mailer.emlix.com (unknown [81.20.119.6]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.emlix.com (Postfix) with ESMTPS id E92B15FAD2; Mon, 16 Sep 2019 15:55:04 +0200 (CEST) Subject: Re: [PATCH 0/4] Fix UART DMA freezes for iMX6 To: Fabio Estevam , Robin Gong , Fugang Duan Cc: linux-kernel , Vinod , Dan Williams , Shawn Guo , Sascha Hauer , NXP Linux Team , Greg Kroah-Hartman , Jiri Slaby , dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-serial@vger.kernel.org References: <20190911144943.21554-1-philipp.puschmann@emlix.com> From: Philipp Puschmann Openpgp: preference=signencrypt Message-ID: <2613a28d-d363-ee4e-679a-e7442e6fde48@emlix.com> Date: Mon, 16 Sep 2019 15:55:04 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: de-DE Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Fabio, Am 12.09.19 um 20:23 schrieb Fabio Estevam: > Hi Philipp, > > Thanks for submitting these fixes. > > On Wed, Sep 11, 2019 at 11:50 AM Philipp Puschmann > wrote: >> >> For some years and since many kernel versions there are reports that >> RX UART DMA channel stops working at one point. So far the usual workaround was >> to disable RX DMA. This patches try to fix the underlying problem. >> >> When a running sdma script does not find any usable destination buffer to put >> its data into it just leads to stopping the channel being scheduled again. As >> solution we we manually retrigger the sdma script for this channel and by this >> dissolve the freeze. >> >> While this seems to work fine so far a further patch in this series increases >> the number of RX DMA periods for UART to reduce use cases running into such >> a situation. >> >> This patch series was tested with the current kernel and backported to >> kernel 4.15 with a special use case using a WL1837MOD via UART and provoking >> the hanging of UART RX DMA within seconds after starting a test application. >> It resulted in well known >> "Bluetooth: hci0: command 0x0408 tx timeout" >> errors and complete stop of UART data reception. Our Bluetooth traffic consists >> of many independent small packets, mostly only a few bytes, causing high usage >> of periods. >> >> >> Philipp Puschmann (4): >> dmaengine: imx-sdma: fix buffer ownership >> dmaengine: imx-sdma: fix dma freezes >> serial: imx: adapt rx buffer and dma periods >> dmaengine: imx-sdma: drop redundant variable > > I have some suggestions: > > 1. Please split this in two series: one for dmaengine and other one for serial > > 2. Please add Fixes tag when appropriate, so that the fixes can be > backported to stable kernels. > > 3. Please Cc Robin and Andy > > Thanks > Thanks for the hints. I will apply them if the contentual feedback is positive. p.s. Did you forget to add Andy? I don't see a Andy in the to- and cc-list.